Original paper
Variability of nucleoid morphology of some cyanophytes growing under various growth conditions
Cepák, Vladislav
Algological Studies/Archiv für Hydrobiologie, Supplement Volumes No. 81 (1996), p. 39 - 52
25 references
published: Sep 18, 1996
DOI: 10.1127/algol_stud/81/1996/39
ArtNo. ESP142011400003, Price: 29.00 €
Abstract
Variability of nucleoid morphology of some cyanophytes in dependence upon various growth conditions was investigated using DAPI fluorescent staining. Nucleoid morphology of individual species is stable under acceptable growth conditions (cell morphology does not change), i. e. in certain spans of temperature and irradiances, which are strain specific. Outside this span it dramatically changes which is distinctly seen in large-celled species. In small-celled strains, fluorescence of DAPI-DNA complexes sharply decreases under adverse growth conditions (mainly high temperatures and irradiances) but no structural changes of nucleoids are visible. In large-celled species ample morphological changes were observed. At the beginning of the action of adverse conditions, DNA material is condensed from one to several DNA nodules of various size and shapes. Later, the brightness of DAPI-DNA complexes decreased, nucleoid becomes pale until it disappears completely. In additions, red fluorescence of chlorophyll becomes weaker and the whole cell shines pale blue. It is assumed that the reduction of brightness is a consequence of splitting double stranded DNA and destruction of supramolecular arrangement ofDNA molecule in cells. In addition, structural changes of nucleoid seem to be the consequence of changes of thylakoid arrangement under adverse growth conditions, which is well documented in Tychonema bourrellyi. The consequences of nucleoid variability for taxonomy of cyanophytes are discussed.
Keywords
Cyanobacteria • cyanophytes • DAPI fluorescent staining • irradiance • growth conditions • nucleoid morphology • temperature